Due to the great work of other forum members it is now possible to create your own dictionaries for the Kobo Glo and Touch, for firmware 2.1.4 or later. Why do this? Well, the dictionaries provided by Kobo are a bit limited, and it is fun anyway to see what can be done.

To use the new dictionaries:

Connect your Kobo to your PC.

On the Kobo go to the ".kobo\dict" folder, and rename "dicthtml.zip" to "dicthtml.backup.zip". This backs up your existing English dictionary (which I assume you already have installed).

Download the appropriate zip file below and unzip it to extract the dicthtml.zip file inside. Do not unzip the dicthtml.zip file.

Copy the dicthtml.zip file to the ".kobo\dict" folder on the reader.

Eject/disconnect your Kobo.

Go into the dictionary screen, e.g., if you have a book open, tap the book icon on the bottom menu, and select Definition.

Flip the language from English to e.g., Deutsch and back again. This makes the Kobo refresh the English dictionary cache. You only have to do this once.

The new dictionary is now ready to use.

It is possible to install the new dictionary to replace one of the other built-in Kobo dictionaries, by replacing the appropriate file with the custom dictionary, e.g., dicthtml-de.zip to replace the Deutsch dictionary. That way you can swop between the Kobo English dictionary and the custom English dictionary.

One minor point: when you view a definition in the custom dictionary the page will still display "Source: Merriam-Webster's English Dictionary" (which is the Kobo dictionary). This description is not actually part of the dictionary file but seems to be held elsewhere in the firmware. You can tell that you are in fact using one of the custom dictionaries because their word definitions usually have an initial upper case letter, whereas in the Kobo Merriam-Webster dictionary they generally start with a lower case letter.

Project Gutenberg notice:

Quote:

This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.net.

Chambers1908.zip: Chamber's Twentieth Century Dictionary of the English Language, Rev. Thomas Davidson (1908), London. Source: Project Gutenberg. Over 33,000 definitions; it is particularly good for British English and historical fiction, as it contains archaic words that are not in the more modern English dictionary supplied with the Kobo. But don't go looking up "twitter" or "facebook"!

Websters1913.zip: Webster's Unabridged Dictionary, various, (1913), USA. Source: originally Project Gutenberg, but I used the excellent epub compiled by MobileRead member nrapallo as my starting point. This dictionary has over 110,000 definitions (compared to the 80,000 or so in the Kobo dictionary), many of them with lengthy descriptions (generally longer than in the Chambers). It is primarily focused on American English spellings; it has British English spellings too, but the definitions simply refer to the American equivalent. For more information about this dictionary, including pronunciation and abbreviation guides, see here.

HowToCreateKoboDictionaries.zip, v 1.1: Instructions on how to create your own custom Kobo dictionaries.

You can install both, and keep the existing Kobo English dictionaries, making three English dictionaries on board, you just have to sacrifice some of the other language dictionaries. For example, if don't want to keep the German and French dictionaries, then rename

.kobo/dict/dicthtml-de.zip to dicthtml-de.backup.zip
.kobo/dict/dicthtml-fr.zip to dicthtml-fr.backup.zip

Then copy the custom dictionaries into .kobo/dict and call them dicthtml-de.zip and dicthtml-fr.zip. Now selecting the German or French dictionary in the reader will actually give you the relevant custom English dictionary.

To go beyond that (add the custom dictionaries as new dictionaries and not replace existing ones) would probably need a change to the firmware.

Are there any other dictionaries available in this format that are ready to use? It would be great to have one with a bit more etymological info, i.e. about word origins, in the definitions. The OED as used by the Kindle does this pretty nicely.

Still, I wonder how you managed to find out that the .html files in the archive were actually gzip files because gzip (on Linux) as well as 7zip (on Windows) are unable to open the ".html" files from the official Kobo dictionaries.
Have you found a way to open the official files ? Or are you aware of any way to do it ?